1. Technical Field
This invention relates generally to cutting systems and more particular to a device for separating a multiple partitioned printed circuit board.
2. Description of the Prior Art
Printed circuit boards are being utilized more in electronic systems as the cost of assembly becomes an increasingly greater part of such systems. To reduce overall manufacturing costs, certain steps have been adopted for assembly of the boards. For example, through-hole components and surface mounted components are conveniently installed in predetermined positions on a printed circuit board by automated equipment such as "pick and place" machines or by a highly skilled operator. To further reduce costs through increased efficiency, in some operations, the through-hole and surface mounted components are assembled on a large substrate that has been previously partitioned into a multiple printed circuit board containing two or more individual circuit boards. This multiple or partitioned printed circuit board is then fully populated with through-hole and surface mounted components at one or more work stations by the automated equipment or operator.
An additional step in the assembly of electronic systems involves the process of separating the partitioned printed circuit board into the individual circuit boards. A number of methods and devices are known and available for performing this operation.
One such method involves a "punch and reinsert" operation wherein the individual circuit boards are punched out of the large substrate before components are inserted thereupon. These circuit boards are then reinserted back into the substrate where they are held by friction while the components are inserted thereupon. Once all the components are inserted, the individual circuit boards are again separated from the substrate. The separation operation involves having an operator warp or distort the substrate such that the individual circuit boards are dislodged. Some stresses are, unfortunately, imparted to the boards through this process and could possibly, damage the boards or the components thereon.
Other methods involve cutting a partitioned printed circuit board once it has been populated with through-hole and surface mounted components. One of these methods involves the use of a band saw which separates the individual circuit boards and also cuts away the excess stock around the border of these boards. This method imparts vibrations to the printed circuit board, however. These vibrations propagate across the board and, in turn, may cause damage to the solder junctions electrically connecting the through-hole and surface mounted components to the board. Also certain surface mounted components are very susceptible to the vibrations from the band saw and may be easily damaged thereby. This method is normally not preferred therefore because of the large vibrations imparted to the printed circuit board through its use.
Another method involves using a water knife cutter which, like the band saw, separates the individual circuit boards and also cuts away the excess stock around the border of these boards. Unlike the band saw, however, the water knife exerts minimal contact pressure on the material being cut due to the small surface area of the water jet stream. Thus, the water knife cutter provides an acceptable method of separating the boards since it exerts minimal stress and vibrations on the boards and therefore the components connected thereon. The disadvantage of this method is the relatively high cost of acquiring a machine employing this type of cutting system.
In keeping with the overall effort to reduce the cost of manufacturing electronic systems, what is desirable, therefore, is an economical device and method that will separate a multiple partitioned printed circuit board into individual circuit board sections without damaging the solder junctions and surface mounted components affixed thereupon.